Such arrangements, quite generally called recoil blocking devices, are specified as obligatory devices for roller-coasters, monorails or the like. They are to come into action when a vehicle moving upward is unable to clear the uphill section for whatever reason and seeks to stop travel backward after stopping. The same device is advantageously used when a vehicle that has come to a standstill must be prevented from moving accidentally backward in the area of a railroad station.
In prior-art recoil blocking devices, the catches are pressed by means of a spring against the toothed rack in a rotationally engaged manner. It shall thus be achieved that the catch will automatically engage the teeth as a consequence of the spring torque if the vehicle should move backward. The drawback of such arrangements is that when an uphill section has been cleared, unpleasant ratchet noises are generated by the fact that the nose of the catch continually comes into contact with the teeth of the toothed rack and is temporarily deflected by same against the spring action.
This drawback is eliminated by the teaching of DE-OS 25 40 547, in which electromagnetic means keep the catch disengaged from the toothed rack depending on a speedometer. However, this suggestion presupposes stationary guides, which bring the catches into contact with the electromagnetic means during the travel of the vehicle past them.